Microfibrillated Cellulose proven to create value in full scale papermaking

Per Svending¹, Edenil Santos da Costa²

¹ Imerys Minerals AB. Sweden
² Imerys do Brasil, Brazil

ABSTRACT

Imerys recently announced the commercial break-through in processing of pulp to microfibrillated cellulose (MFC) for use in paper industry applications. Imerys’ MFC offers paper makers the opportunity to become more cost competitive or to develop new differentiated products. Application experience from full scale papermaking is presented with emphasis on how cost savings can be achieved when replacing market pulp with filler and MFC. Further there are examples of how MFC can help the paper maker improve quality of paper as well as paper coatings.

Keywords: MFC, microfibrillated cellulose, filler, opacity, porosity, coating

History and current state of the art of “conventional” MFC.

• First made in the 80’s
  • Very high energy demand (25-30 MWh/ton)
  • Using expensive and sophisticated grinding equipment
  • Expensive and very high capex/capacity ratio
• Known to be ideal as a strength aid in paper.
• Conventional state of the art MFC
  • Pulp pre-treatment to soften up the fibers
  • Significantly reduced energy demand
  • Still using expensive and sophisticated grinding equipment resulting in high capex/capacity ratio
  • Low solids product in gel form, often with high surface charge
  • Scale limitations preventing large volume applications

In practice “conventional” MFC is still restricted to high value applications.

FiberLean MFC is made from co-grinding pulp with filler

Full scale trial experience with FiberLean

• Close to 50 full scale trials on 21 paper machines to date
  • In Europé, North America, South America and Asia.
• Trials ranging from a few hours to several days.
• Extensive experience across segments
  • 6 mills in UWF
  • 6 mills in speciality and mechanical paper
  • 8 mills in CWF
  • 2 mills in Packaging
• 3 commercial contracts for on-site MFC plants.

FiberLean MFC base concept:

Facilitating increased filler content in papers.

Relative USD pulp price trend from April 2013

• The gap between long and short fiber is back to what it was

Adding price trend in EUR paints another picture

• In EUR terms the price of pulp is now 15-20% higher!

Simplistic value calculation model for filler increase with MFC

Numerics of value calculation model for filler increase with MFC

• In order to start creating value the price of MFC conversion needs to be below 2 500 $/dry metric ton.
• Obviously it needs to be well below this to make filler increase worthwhile for the paper maker.

Tensile strength is improved by MFC addition

Tensile Energy Absorption increases more than tensile, i.e. stretch is improved.

Tear strength improves too, a result of better fiber network bonding.

Opacity improves with higher filler loading, but also from MFC

The impact of MFC on porosity is quite profound

* Also going from 9 nips to 6 nips.

MFC has a strong positive impact on initial wet web strength

MFC is a good fit for increased filler loading

Key differerentiators compared to chemistry based concepts

FiberLean MFC coating improvements:

Improved coating performance through better base paper hold-out.

Opportunities from porosity reduction in base paper

• Reduced coat weight
• Improved gloss and smoothness
• Reduced calendering to win bulk (to compensate for filler increase)
• Use of cheaper coating pigments
• Reduced binder demand
• Better coater runnability

Less coating needed to get good coverage

FiberLean MFC for product development:

Improved paper quality through use of MFC.

Adding MFC to a 250 CSF base at constant filler content (20%) to improve paper properties

Adding MFC to a 550 CSF base at constant filler content (20%) to improve paper properties

Conclusions:

• Use of MFC for P&W paper cost reduction or quality improvement is now established in the market.
• Cost of MFC conversion needs to be (well) under € 2 500 per dry ton.
• This is possible using an on-site MFC process with economy of scale.